Process for the polymerization of olefins



United States Patent 3,424,737 PROCESS FOR THE POLYMERIZATION OF OLEFINSAlldl' Delbouille, Brussels, and Henry Toussaint, Schaerbeek, Brussels,Belgium, assignors to Solvay & Cie, a simple of the Kingdom of BelgiumNo Drawing. Filed Oct. 2, 1964, Ser. No. 401,234 Claims priority,appligcation France, Jan. 3, 1964,

US. Cl. 260-943 7 Claims Int. Cl. C081? 1/28, 3/02; B01j 11/84 ABSTRACTOF THE DISCLOSURE A process for polymerizing at least one l-olefin suchas ethylene with a catalyst which forms on comingling a sandwichcompound such as bis(cyclopentadienyl) titanium chloride, a tin or leadcompound such as tetrabutyl tin and a halide of aluminum or boron suchas aluminum chloride.

This invention relates to catalysts which are useful for thepolymerization and copolymerization of alpha olefins, especiallyethylene.

It is known to utilize, for the polymerization of ethylene, or otheralpha olefins, ternary catalysts formed from:

(a) A metal, a halide or an organometallic compound of a metal ofSubgroup b of Groups IV, V and VI of the Periodic Table (b) A halide ofan element of Subgroup a of Groups IV, V and VI; and

(c) A halide of an element of Group IH or V (Belgian Patent 547,618).

Ingredients (a) include the tetraalkyls and tetraaryls of tin and oflead, especially those containing up to 40 carbon atoms per molecule,e.g., tetraethyl lead, tetrapropyl lead, tetrabutyl lead, tetraphenyllead, tetranaphthyl lead, and the corresponding compounds of tin. Thetin tetraalkyls produce especially active catalysts.

Ingredients (b) include the mineral acid salts of titanium, vanadium,chromium, molybdenum, and tungsten, the halides of titanium beingfrequently used.

Ingredients (c) include the halides of aluminum, of antimony, and ofboron. Especially suitable are aluminum trichloride, antimonypentachloride, and boron trifiuoride. This ternary catalyst allowsolefin polymers of high molecular weight to be obtained under favorableconditions and with very good productivity.

Such catalysts are, for example, formed as products of the reaction of alead or a tin alkyl with titanium tetrachloride or a vanadium chloridein the presence of aluminum chloride or a halide of boron. Suchcatalysts promote the formation of linear polyethylenes having highmolecular weight and a density of the order of 0.955.

An object of this invention is to provide an improved polymerizationcatalyst. Another object is to produce solid olefin polymers havingimproved properties. Other objects and advantages will become apparentto those skilled in the art on considering this disclosure.

It has now been discovered that the polymerization of ethylene andhigher alpha-olefins can be effected by using a catalyst system obtainedby the reaction of a metal, a halide or an organometal compound ofGroups IVb, Vb and VII) of the Periodic Table with a halide of anelement of Group III or V and a sandwich compound of a transitionelement selected from Groups IVa, Va, VIa and VIII of the PeriodicTable, this compound being substituted for ingredient (b), supra.

Lange, N. A., Handbook of Chemistry, 4th ed., 1941, Sandusky, Ohio,Handbook Publishers, Inc., pages 18 and 19.

This process is particularly applicable to the polymerization ofethylene and higher olefins such as, for example, propylene, l-butene,l-pentene and 4-methyl-1-pentene. This list is not exhaustive.Furthermore, the process includes the copolymerization of ethylene withhigher olefins or of the latter among themselves.

One advantageous method of carrying out the process of polymerizationaccording to this invention comprises forming the catalyst by thereaction of an alkyl lead or an alkyl tin (alkyl groups having up to 10carbon atoms each) and anhydrous aluminum chloride or an anhydrous boronhalide with a sandwich compound of a transition metal such as titanium,vanadium, zirconium, chromium, cobalt, iron or nickel. The sandwichcompounds which are preferred are, for example, the bis-cyclopentadienylderivatives of these meals, especially the bis-cyclopentadienyl titaniumchlorides, the bis-cyclopentadienyl vanadium chlorides, andbis-cyclopentadienyl vanadium oxychloride. Di-benzene chromium,di-toluene chromium, and biscyclopentadienyl cobalt are also operative.

The polymerization can be efiected at temperatures in the range 0 to C.,pressures in the range 1 to 50 atmospheres, and reaction times in therange 15 minutes to 50 hours. These are not absolute limitations.Conditions outside these ranges can be used.

According to the invention, the polymerization can be conductedcontinuously or batchwise in homogeneous phase, Although all inertsolvents are suitable, and particularly all the inert hydrocarbons, thebest results are obtained when the catalyst is dissolved in an aromaticsolvent. In general, the preferred solvents are benzene, toluene, theXylenes, and the like.

The product polymers obtained by the use of the catalysts hereinbeforedescribed are formed in good yields, and the catalyst activity isoptimum, when the molar ratio between the Group III or V element halideand the first constituent of the catalyst system, particularly the molarratio between the aluminum compound and the tin or lead derivative, iswithin the range 0.1:1 to 2: 1. In accordance with this invention, themolar ratio of Group III or V element halide to sandwich compound isusually in the range 1:1 to 5:1. Ratios outside this range areoperative.

According to the process of this invention, polymers are obtained whichhave density and rigidity clearly superior to those of correspondingpolymers obtained by processes known in the prior art. In fact, thepolymer product obtained is essentially linear since it contains lessthan one methyl group per thousand carbon atoms. Furthermore, asignificant dilierence in the number of carbon-carbon double bonds whichare internal and terminal is observed. The result is an appreciableincrease in the density and the crystallinity.

The high density of the polymer together with its high rigidityconstitute an appreciable improvement, the advantage of which is evidentin the fabrication of articles by injection. Injection molded articlesdo not exhibit distortions which are present in certain cases in similararticles injection molded utilizing polyethylenes known in the priorart.

The following examples are given as illustrative.

EXAMPLE I The polymerization of ethylene is effected in the presence ofa ternary catalyst (C H TiCl -Sn(C H A101 Into a one liter autoclave,109 milligrams of bis-cyclopentadienyl titanium chloride and ahomogeneous solution (concentration 200 grams per liter), in xylene, ofa mixture of aluminum chloride and tetra(n-butyl) tin are introduced ata mo] ratio of 0.475 :0.525, respectively, the mol ratio of aluminum totitanium being 3.08:1. The catalyst 3 4 system is homogenized by theaddition of 100 cc. of TABLE H benzene. The color of the resultingsolution is green. 1 D G k Before proceeding with the polymerization,one adds Matem e about 500 cc. of benzene. A partial pressure ofethylene of E 1 O 7 260 3 700 9.04 kilograms per square centimeter (129p.s.i.) is main- 5 gg :32 120 1 3 tamed m'the autoclave together with atemperature of Pol eth lenelwas reduced withacatal st re ared fromtitanium o C After 180 the reactlon 13 P? and thiajre tetrach l orid e,tin tetra En-butyl) and 8.11111111 1 1111? cl i loride according to 1srecovered 12 grams of polyethylene havlng a density Belgian Patent547,618. (ASTM Methods D12486QT and P 0-959 The data in Table II showthat the rigidity of the polygm/ccand a nlolecular Welght (base? onvlscPslty 10 ethylene produced according to this invention is clearlyurement at 160 C. of the polymer dissolved in tetralm) higher to that ofpolymers previously produced with of other catalysts.

EXAMPLES In AND 1V Polyethylene prepared according to the process ofthis The polymerization of ethylene according to Example I invention ischaracterized by a partlcular structure and is repeated with differentquantities of reagents. The reespecially by exceptional linearity. sultsare shown in Table I. Shown in Table III are values of density ofdifferent TABLE 1 H o H PC2134, D t' G M 1 1 No. (on 31 3 191? giir.kgJcm. (P.s.i.) pal y :5 weigii is as d on viscosity 2 0. 110 0. 122 0.33s 8. e (122) 199 12 108, 000 a o. 127 0. 194 0. 606 7. s (104) 210 1972, 000 4 0. 116 0. 146 0. 984 7. 7 (110) 150 13 51, 000

samples of polyethylene produced according to the proc- EXAMPLEV ess ofthe invention and corresponding values of samples The catalyst isprepared by introducing 300 mg. of bisof thisame molefmlar Welghtprodufed under F f cyclopentadienyl titanium chloride into a 250 cc.cylinder butwlth catalyst obtamfid from K111111111 which is dry and hasbeen swept out with nitrogen. After tetrachlonde Place of thebls'cyclopentadlenyl dissolution in 100 cc. of benzene, there is added3.83 grams compoundof a homogeneous solution of aluminum chloride andTABLE III tetra(n-butyl) tin in a mole ratio of 0475:0525, respec-Density of polyethyltively. The catalyst is allowed to age for 15mlnutes at Mo ec r We g Density, -l @116 028mm m ar room temperature.welghtv gm/cc- The catalyst system is introduced into a stainless steel27,000 0.967 0. 95s autoclave which has a three-liter capacity, is dry,and has 52,000 8: 3 32; been swept out with nitrogen and which contains900 cc.

1 Catalyst: (C5H5) 2TiC12sXl(C4Hn)4A1C13.

of pure benzene. After introduction into the autoclave the catalystdissolves totally and a greenish color appears.

Polymerization is eifected at 25 C. for 235 minutes at an averageethylene pressure of 11.5 kilograms per square centimeter (164 p.s.i.).After cessation of the polymeriza- 1 Catalyst: TiClSn(C H )AiCl;according to Belgian Patent 547,618

The different types of unsaturation of the polyethylene product, asdetermined by infrared spectrophotometry, are shown in Table IV.

TABLE IV Number of groups per thousand carbon atoms Polyethylene C=C R-CH=C Ha C=C H) --C H;

H R R (trans) (vinyl) (vinylidene) (methyl) High pressure (A) 0. 07 0.08 0.3 10 High pressure (B) 0. 05-0. 0. 07-0. 1 0. 9-1. 3 20 Highpressure (0) 0. 1 0. 09 0. 4.1 23 Catalyst formed from alkylaluminum 0.01 0. 16 0. 05 1-5 0. 03-0. 04 1. 3 0. 02 2 Chromium oxide catalyst (B)0. 08 1. 4 1. 5 According to Belgian Patent 547,618. 0. 36 0. 0. 06 1Product according to the invention,

Example V 0. 083 0. 160 0. 014 0. 2

Comparison of these values with those of polyethylenes produced byprocesses known in the prior art shows that the polymer obtainedaccording to this invention is extremely linear and that it isdifferentiated by a very low content of vinylidene unsaturation. It isthus distinguished from all prior polyethylenes. This perfect linearity,the almost total absence of methyl groups and the low vinylidene contentare consonant with a high density of the new polyethylene, which densityis higher than those of polymers previously obtained.

These high-density polymers are characterized by a high rigidity, whichfacilitates the fabrication of articles by injection molding withoutproducing undesirable distortions.

The so-called sandwich compounds referred to herein are well known inthe art; see, for example, U.S. Patent 2,827,446 (1958), Breslow et al.I. Am. Chem. Soc. 79, 5072-3 (1957), Natta et al., ibid. 79, 2975-6(1957).

The following is claimed:

1. A process which comprises homopolymerizing ethylene to solid polymerin the presence of a catalyst which forms on comminglingbis(dicyclopentadienyl) titanium dichloride, tetrabutyl tin, andaluminum chloride.

2. A process according to claim 1 wherein the catalyst is dissolved inan inert hydrocarbon solvent, the mol ratio of aluminum chloride totetrabutyl tin is in the range 0.1:1-221, the molar ratio of aluminumchloride to his (cyclopentadienyl) titanium chloride is in the range 1:1to 5:1, the polymerization temperature is in the range 0 to 100 C. andthe polymerization pressure is in the range 1 to 50 atmospheres.

3. A process which comprises polymerizing at least one l-olefin in thepresence of a catalyst which forms on commingling (A) a sandwichcompound selected from the group consisting of bis(cyclopentadienyl)titanium dichloride, bis(cyclopentadienyl) vanadium trichloride,bis(cyclopentadienyl) vanadium oxychloride, and bis(cyclopentadienyl)cobalt;

(B) a compound selected from the group consisting of tin and leadcompounds having the formula SnR and PbR respectively, wherein R is ahydrocarbon radical selected from the group consisting of alkyl, aryl,and cycloalkyl radicals having from 1 to carbon atoms each; and

(C) a compound selected from the group consisting of the halides ofaluminum and boron.

4. A polymerization catalyst which forms on comminglingbis(cyclopentadienyl) titanium dichloride, tetrabutyl tin, and aluminumchloride, the molar ratio of aluminum to tin compound being in the range0.1:1 to 2:1 and the ratio of aluminum to titanium compound being in therange 1:1 to 5:1.

5. A catalyst which forms on commingling (A) a sandwich compoundselected from the group consisting of bis(cyclopentadienyl) titaniumdichloride, bis(cyclopentadienyl) vanadium trichloride,bis(cyclopentadienyl) vanadium oxychloride, and bis(cyclopentadienyl)cobalt.

(B) a compound having a formula selected from the group SnR; and PbRwherein R signifies a hydrocarbon radical selected from the groupconsisting of alkyl, aryl and cycloalkyl radicals having from 1 to 10carbon atoms each; and

(C) a compound selected from the group consisting of the halides ofaluminum and boron.

6. A catalyst according to claim 4 dissolved in an inert hydrocarbonsolvent selected from the group consisting of benzene, toluene and theXylenes.

7. A process according to claim 3 wherein said l-olefins are selectedfrom the group consisting of ethylene, propylene, l-butene, l-pentene,and 4-methy1-1-pentene.

Raff and Allison: Polyethylene, Interscience Publishers, Inc., 1956 (pp1-4).

JOSEPH L. SCHOFER, Primary Examiner.

M. B. KURTZMAN, Assistant Examiner.

U.S. Cl. X.R.

